The broad long-term goals of the proposed research are to identify basic mechanisms that control vascular morphogenesis in brain and thereby identify new rational drug-based strategies for normalizing pathological blood vessels that form in response to ischemia and trauma. A parallel goal is to understand the molecular and cellular mechanisms responsible for pathological angiogenesis in brain. The working hypothesis for the proposed research is that pathological angiogenesis is a consequence of aberrant vascular morphogenesis and that significant improvement can be achieved with pharmacological intervention, particularly through appropriate targeting of cytoskeletal signaling pathways in the endothelium. The serious defects associated with pathological angiogenesis, including impaired blood flow and vessel hyper-permeability, likely contribute to neurological deficit following ischemic injury. Timely rectification of vascular defects through pharmacological intervention offers the promise of improved neurological outcomes in patients with brain ischemia and trauma. To address these goals, two aims are proposed. The first aim is: In vitro, define signaling pathways that regulate assembly of brain microvascular endothelial cells (BMVECs) into capillary-like structures;and identify a panel of pharmacologically active drugs that modulate these signaling pathways and thereby facilitate vascular morphogenesis. Key goals in this first aim are to define signaling pathways and effector molecules that regulate formation of capillary structures by BMVECs in vitro, with emphasis on Rho GTPases, GSK-3b, and calpain;and to identify drugs that selectively target these pathways and effector molecules in BMVECs and thereby improve formation of capillary structures in vitro. Experimental tools will include retroviral transduction of BMVECs with specific signaling mutants, in vitro capillary morphogenesis assays, in vitro analyses of cell:cell junctions, and pharmacological agents that modulate the activities of Rho GTPases, GSK- 3b, and calpain. The second aim is: In vivo, with a mouse model of VEGF-driven angiogenesis in adult brain, identify rational drug-based strategies for improving both the architecture and function of pathological neovessels. Key goals in this second aim are to identify, with the benefit of findings made in Aim 1, drug-based strategies that normalize aberrant vessel architecture and vascular perfusion, normalize basement membrane and pericyte coverage, and reduce vascular hyper-permeability in brain. Experimental methods will involve a mouse model of pathological angiogenesis in brain, together with microscopic analyses of vascular structure, perfusion, and hyper-permeability. PUBLIC HEALTH RELEVANCE: The goals of this research are to identify basic mechanisms that regulate formation of new blood vessels in adult brain and thereby design new strategies for correcting serious defects commonly associated with disordered blood vessel development. Understanding mechanisms responsible for defective blood vessels in brain is important because stroke and traumatic injury result in formation of blood vessels with abnormal vascular structure and such abnormalities contribute to neurological impairment. Thus, new strategies to correct vascular abnormalities in brain are important for improving patient recovery and clinical outcomes.